Every time it seems the president has zeroed in on an issue, and appears determined to see it through — guns and immigration are just the two latest examples — he moves on to something else. And Congress, which isn’t designed to respond swiftly to national events and the wishes of the White House even in the least distracted of circumstances, simply can’t keep up.

The hyperactive mind-set of the Oval Office has had the effect, whether by design or not, of quickly diverting attention from topics big or small. After a bout of attention on gun control in the wake of the Florida school massacre last month, Congress has seemingly moved on already. Before that, it was the plight of Dreamers facing deportation.

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In the end, nothing gets done on the issue of the day.

The president “is all over the place — 15 tweets in 19 hours,” said Senate Minority Whip Dick Durbin (D-Ill.), who invested months of his time in the immigration debate only to watch the effort fall apart. “Trying to keep up with where his mind lights from day to day is hard."

Trump’s March 5 deadline to extend expiring protections for some young immigrants briefly trained the Senate on that topic, though the chamber failed to pass anything. Then the president flirted with Democrats on gun control after the Florida school massacre, seemingly building momentum for a rare breakthrough.

But before anything happened on the Hill, Trump had moved on tariffs — causing a genuine GOP freak-out and a movement to rein in Trump. When the White House might try to refocus the Capitol’s attention back on gun violence or immigration is anyone’s guess.

“Short attention span around here. Obviously on guns, you don’t do that one unless you’re forced. On immigration, there’s no real deadline,” said Jeff Flake (R-Ariz.), a retiring senator also in the middle of both issues. He said he’s worried he’ll end his Senate career this year without Congress having taken action on either issue.

The lone exception in the Senate is Majority Leader Mitch McConnell (R-Ky.), who refuses to let media coverage or the whims of the White House dictate his floor schedule. McConnell shelved the gun debate while it was in the media spotlight, instead plugging away at confirming lifetime judicial appointments. He's thus far declined to devote time even to a bill backed by the National Rifle Association to modestly improve the background check system.

Last year's tax reform push and doomed attempt at repealing Obamacare, on the other hand, each occupied months of time.

All of which is to say that the Senate is occasionally capable of focusing — when the focus is on something McConnell really wants.

“Congress has a very adequate attention span when it comes to helping special interests,” said Sen. Sherrod Brown (D-Ohio). “It’s things that the public wants, [but] that the interest groups that run the Republican Party don’t want where the attention span is short.”

McConnell’s No. 2, Majority Whip John Cornyn, said he's still working on his bill to shore up the background check system.

“This issue is not going away," Cornyn said. "We’re kind of at an inflection point on this whole topic and I want to make sure we get it done and get it done right.”

But by the time any debate on the bill might happen, Congress will be more than a month removed from the school shooting. Some lawmakers say the media's whims don't help, either.

“You’re not much better than we are, are you?" Sen. Joe Manchin (D-W.Va.) told a reporter who asked about Congress' attention deficit.

Before guns, it was immigration. In that case, McConnell set aside a week in February to debate the topic — but only as part of a deal to get Democrats to agree to reopen the government. (The weeklong exercise yielded a lot of acrimony and precisely zero new laws to help Dreamers.)

Gun control activists have vowed to keep the heat on Congress, and Democratic leaders believe that nationwide demonstrations scheduled for March 24 will help. With federal court rulings effectively preventing the Trump administration from executing its plans to end Obama-era protections for young immigrants, advocates for that issue appear ready to take their chances with the judiciary after falling short in Congress.

But ultimately, like lawmakers, they’re at the mercy of Trump’s outsize power to control a Washington agenda that now changes at head-snapping speed.